The present invention relates to an apparatus capable of surely removing a toner or similar image forming substance deposited stably on a sheet by a copier, facsimile machine, printer or similar image forming equipment, and a sheet processing apparatus.
A method and an apparatus for removing a toner or similar image forming substance from a sheet, or recording, produced by image forming equipment have been proposed in various forms in the past. Among them, a toner removing method disclosed in, for example, Japanese Patent Laid-Open Publication No. 1-101576 immerses a sheet carrying a toner thereon in a solvent which dissolves the toner, or resin, and then applies ultrasonic oscillations to the sheet, thereby separating the toner from the sheet. In a method taught in Japanese Patent Laid-Open Publication No. 4-300395, a solvent is deposited on the printed portions of a waste sheet by immersion, spraying, application or similar technology so as to dissolve the toner. In this kind of method, the dissolved toner is removed by, for example, rinsing, air suction, contact with an adsorbent, mechanical or electrical separation, or electrostatic adsorption. Subsequently, the sheet is rolled or otherwise finished to be recycled.
A method not using a solvent and disclosed in, for example, Japanese Patent Laid-Open Publication No. 2-55195 removes a thermally fusible ink or toner deposited, by an electrophotographic system or a thermal transfer system, on a printing consisting of a substrate and a parting agent applied to the substrate. Specifically, this method lays an ink separating body on the printing, conveys them through between a heat roller and a press roller, and removes, after they have been cooled off, the ink separating body from the printing. As a result, the ink is transferred from the printing to the ink separating body. Japanese Patent Laid-Open Publication No. 4-64472 proposes an eraser made up of an endless sheet having at least the surface thereof implemented by a thermally fusible resin, a heat roller and a cool roller each being rotatable while supporting the endless sheet, a press roller for pressing a sheet (erasable paper), whose surface has been treated for parting, against the softened or melted resin, and a drive section for driving them. Further, Japanese Patent Laid-Open Publication No. 4-82983 proposes an image forming substance removing apparatus having two parallel rollers rotatable in contact with each other and allowing a sheet to pass through the nip portion thereof, a heater for heating at least one of the rollers, a scraper for separating the sheet moved away from the nip portion from the rollers, and a removing device for removing an image forming substance from the rollers.
Assume that an image forming substance contains a thermally fusible resin as a major component thereof, and that it is deposited by, for example, a fixing step included in an electrophotographic process on a plain paper or similar paper whose fibers appear on the surface. Then, the image forming substance firmly coheres to the fibers of the paper. Hence, if the substance is removed from the sheet by any of the conventional methods and apparatuses not using a solvent, even the fibers are stripped off the sheet together with the substance, damaging the entire sheet. Particularly, when heat and pressure are applied to the ink separating body, endless sheet or rollers in order to promote the removal of the image forming substance, the cohesion of the substance to the sheet is rather enhanced, depending on various conditions.
In light of the above, a sheet or recording may be infiltrated with at least one of water or labilizing agent, aqueous solution containing a surface active agent, aqueous solution containing a water-soluble polymer, and aqueous solution containing both a surface active agent and a water-soluble polymer. An image forming substance carried on the wet sheet is caused to adhere to an intermediary separating member by heat or pressure. As a result, the substance is removed from the sheet. This kind of scheme is taught in, for example, Japanese Patent Application No. 4-255916. With this method, it is possible to remove only the image forming substance without damaging the sheet noticeably. Of course, if the sheet from which the substance has just been removed still contains the liquid, it is not feasible for image formation using, for example, an electrophotographic copier Preferably, therefore, the sheet should be subjected to postprocessing for removing the liquid.
The postprocessing, however, brings about some problems, as follows. Assume that to evaporate the liquid, the sheet infiltrated with the liquid is conveyed by being nipped in the widthwise direction thereof by a plurality of conveying means which move at the same speed. Then, the sheet is likely to crease, tear off or fold. When the sheet is simply brought into contact with the liquid to retain it therein, it is likely that the liquid fails to infiltrate into the sheet sufficiently, preventing the image forming substance from being removed in the expected manner. Moreover, not only the image forming substance but also the fibers of the sheet are removed from the sheet, depending on the softening degree of the substance.
On the other hand, Japanese Patent Application No. 4-255915, for example, teaches a method which infiltrates a fresh sheet with a liquid selected from water, aqueous solution containing a surface active agent, aqueous solution containing a water-soluble polymer, and aqueous solution containing both a surface active agent and a water-soluble polymer, and then dries the sheet. The sheet undergone such processing is used for conventional image formation, and then the image forming substance is removed by the above-stated method for reuse. With this processing, it is also desirable to remove, after the sheet has been infiltrated with the liquid, excessive part of the liquid by heating or otherwise treating the sheet. However, this kind of treatment also brings about the crease, breakage or fold problem discussed previously. Again, when the sheet is simply brought into contact with the liquid to retain it therein, it is likely that the liquid fails to infiltrate into the sheet sufficiently, preventing the image forming substance from being removed in the expected manner. Moreover, not only the image forming substance but also the fibers of the sheet are removed from the sheet, depending on the softening degree of the substance. In addition, when the liquid is supplied to the sheet by a liquid supply member whose surface moves in an endless fashion while carrying the liquid thereon, it is likely that a sufficient amount of liquid cannot be supplied to the sheet.
Other prior art technologies relating to the present invention are listed below.
(1) Japanese Patent Laid-Open Publication No. 60-133458
(2) Japanese Patent Laid-Open Publication No. 4-22968
(3) Japanese Patent Laid-Open Publication No. 4-300395
(4) Japanese Patent Laid-Open Publication No. 4-327299
(5) Japanese Utility Model Laid-Open Publication No. 2-117547
(6) Japanese Utility Model Laid-Open Publication No. 4-118499
(7) Japanese Utility Model Laid-Open Publication No. 4-118500
(8) Japanese Patent Laid-Open Publication No. 51-100728
(9) Japanese Patent Laid-Open Publication No. 57-125962
(10) Japanese Patent Laid-Open Publication No. 57-125963
(11) Japanese Patent Laid-Open Publication No. 59-2069
(12) Japanese Patent Laid-Open Publication No. 59-89372
(13) Japanese Patent Laid-Open Publication No. 59-93764
(14) Japanese Patent Laid-Open Publication No. 62-102270
(15) Japanese Patent Laid-Open Publication No. 64-101576
(16) Japanese Patent Laid-Open Publication No. 64-101577
(17) Japanese Patent Laid-Open Publication No. 3-249661
(18) Japanese Patent Laid-Open Publication No. 4-356085
(19) Japanese Patent Laid-Open Publication No. 4-356086
(20) Japanese Patent Laid-Open Publication No. 4-356087
(21) Japanese Patent Laid-Open Publication No. 4-356088
(22) Japanese Patent Laid-Open Publication No. 4-356089
(23) Japanese Patent Laid-Open Publication No. 4-91298
(24) Japanese Patent Laid-Open Publication No. 4-281096
(25) Japanese Patent Laid-Open Publication No. 57-114171
(26) Japanese Patent Laid-Open Publication No. 5-2356
(27) Japanese Patent Laid-Open Publication No. 5-127571
(28) Japanese Patent Laid-Open Publication No. 5-61382
(29) Japanese Utility Model Laid-Open Publication No. 63-140577
(30) Japanese Patent Laid-Open Publication No. 2-111987
(31) Japanese Patent Laid-Open Publication No. 1-137266
(32) Japanese Patent Laid-Open Publication No. 1-297294
(33) Japanese Patent Laid-Open Publication No. 4-333699
(34) Japanese Patent Laid-Open Publication No. 4-333088
(35) Japanese Patent Laid-Open Publication No. 4-64473
(36) U.S. Ser. No. 08/115,194 (filed Aug. 31, 1993)
(37) European Pat. Appln. No. 93113920 (filed Aug. 31, 1993)